System and method for providing mutual breakpoint capabilities in a computing device

ABSTRACT

A system having at least one breakpoint generating module and a core processor and method for providing mutual breakpoint capabilities to at least one breakpoint generating module and a core processor in a computing device. Each breakpoint generating module is capable of generating a first breakpoint message for allowing operation of the core processor and each breakpoint generating module to be halted. A second breakpoint message allows operation of the core processor to be halted. The second breakpoint message corresponds to the first breakpoint message. In addition, the core processor generates a third breakpoint message for allowing operation of the core processor and each breakpoint generating module to be halted.

This is a division of copending parent application Ser. No. 10/986,430, filed Nov. 12, 2004, and claims the benefit of U.S. Provisional Appln. No. 60/612,859, filed Sep. 27. 2004.

FIELD OF THE INVENTION

This invention relates to providing breakpoint capabilities in a computing device. More specifically, the invention relates to providing mutual breakpoint capabilities to at least one breakpoint generating module and a core processor in a computing device.

BACKGROUND OF THE INVENTION

FIG. 1 is a block diagram illustrating a computer system 101 implementing a Direct Memory Access controller (referred to hereinafter as “DMA”) according to one embodiment of the invention. A core processor 102 and a DMA controller 103 both access data stored in the system's main memory 104. A Memory Interface Unit (“MIU”) 105 is used as an interface to the memory, enabling the DMA controller and the core processor to access data stored therein. The main memory 104 can be divided into several address spaces such as a data memory space 106 and a program memory space 107. Among its other roles, the MIU 105 prevents conflicts resulting when the core processor 102 and the DMA controller 103 try to access the same memory address at the same time. Data is channeled between the DMA controller 103 and the MIU 105 via a data bus 108 and between the MIU 105 and the core processor 102 via a data bus 109. Likewise, data is channeled between the MIU 105 and the data memory space 106 via a data bus 110 and between the MIU 105 and the program memory space 107 via a data bus 111.

During processing it is often required to rearrange data and/or to move data segments from one location in memory to another location, i.e. “data transfer”. Data transfer can be performed by the core processor 102, however, it is considered as a bottleneck to the core processor's operation. In the absence of a DMA controller 103, the core processor 102 dedicates timeslots for memory management, which would otherwise be dedicated to core processing computations. Therefore, it is the responsibility of the DMA controller 103 to manage and transfer data stored in memory, memory management that is performed in parallel to the core processor's operation. The DMA controller 103 transfers data from a source location to a destination location, or in other words, from source addresses to destination addresses.

The core processor 102 then accesses the data in the destination location, performing operations thereon. Sometimes it may happen that the core processor 102 and the DMA controller 103 both try to access the same memory address at the same time, a situation that gives rise to a conflict whose result is indefinite. In order to prevent such conflicts from occurring, memory access (done by the DMA controller or by the core processor) is performed by the Memory Interface Unit (MIU) 105.

Operation of microprocessors (such as the core processor 102) and other hardware components (such as the DMA controller 103) can be disabled/enabled in several known ways. For example, U.S. Pat. No. 5,978,860 (“System and method for disabling and re-enabling at least one peripheral device in a computer system by masking a device-configuration-space-access-signal with a disable or re-enable signal”, Dell USA, L.P., published 1999) discloses a system and a method for disabling and re-enabling peripheral devices (PDs) in a computer system. The system includes a CPU, a host bus coupled to the CPU, a host-bus-to-peripheral-device-bus (HB/PDB) bridge coupled to the host bus, at least one PD, at least one peripheral device bus coupling the HB/PDB bridge and at least one PD. The system also includes a device, typically in the form of a digital gate, for selectively disabling and re-enabling at least one PD. The method of U.S. Pat. No. 5,978,860 operates in connection with a computer system having a CPU, a HB/PDB bridge coupled to the CPU and capable of sending a device-configuration-space-access-signal (DCSAS) to the DCSAS input pin of a target PD when attempting an access operation, such as a read or a write operation, on the target PD, and one or more system I/O registers having a CONFIG ENABLE bit that reflects a user's request to disable or re-enable a PD. The method intercepts the DCSAS before it reaches the DCSAS input pin of the target PD, provides the intercepted DCSAS to the input of a digital gate such as an AND gate, provides a signal corresponding to the CONFIG ENABLE bit to the input of the same digital gate, and delivers the resulting output signal from the digital gate to the DCSAS input pin of the target PD.

In addition, during development of software and hardware systems, it is sometimes required to debug the operation of the core processor 102 and the DMA controller 103.

Currently in the art there are several methods that allow debugging operation of a DMA controller. For example, EP 927,938 (“Data transfer method and device”, published 1999, assigned to Sony Computer Entertainment Inc) discloses debugging of a system which performs DMA transfer between different buses through a buffer. In EP 927,938, a first bus and a second bus are connected through a bus repeater, which has a buffer memory and two DMA (direct memory access) controllers that are connected to the first and second buses, respectively. The bus repeater can send DMA requests to the DMA controllers, and two CPUs can mask those DMA requests. A first of the two DMA controllers transfers data on the first bus to and from a buffer memory in the bus repeater, and the second DMA controller performs DMA transfer between the buffer memory and the second bus. A first of the two CPUs masks the DMA requests of the bus repeater and accesses the buffer directly to check the DMA function.

JP 1142848 (“Address trapping circuit”, published 1989, assigned to NEC Corp) discloses a method for checking the normality of data during data transfer by latching data on a data bus with an address signal outputted from a register circuit coincident with an address signal outputted from a direct memory access (DMA) controller to stop DMA operation.

In addition, it is possible to halt the operation of a core processor 102, for example in order to debug its operation, a procedure referred to as a breakpoint. However, when the core processor is halted, the DMA controller 103 can continue transferring data. In such case, the state of the registers and buses, such as the buses 108, 110 and 111 (together composing “data state”) can change while debugging, and the developer can get wrong impression of the data state that characterizing the system at any step. Thus, it would be clearly be desirable to solve this drawback by providing a way to halt the DMA when halting the CPU.

In addition, when halting the DMA, in any method known in the art, it is sometimes preferred that the core processor halts as well, preventing it from modifying, for example, the state of the memory or the buses (such as buses 109, 110 and 111). That is, mutual breakpoint capabilities are beneficial for debugging a computing system including a DMA controller.

SUMMARY OF THE INVENTION

The present invention provides a system for providing mutual breakpoint capabilities to at least one breakpoint generating module and a core processor in a computing device, the system comprising:

-   -   at least one breakpoint generating module capable of generating         a first breakpoint message for allowing operation of the core         processor and the at least one breakpoint generating module to         be halted; and     -   a core processor coupled to said at least one breakpoint         generating module and being responsive to a second breakpoint         message for allowing operation of said core processor to be         halted;     -   wherein the second breakpoint message corresponds to the first         breakpoint message; and     -   wherein the core processor generates a third breakpoint message         or allowing operation of the core processor and the at least one         breakpoint generating module to be halted.

The present invention further provides a system for providing mutual breakpoint capabilities to at least one breakpoint generating module and a core processor in a computing device, the system comprising:

-   -   at least one breakpoint generating module capable of generating         a first breakpoint message for allowing operation of the core         processor and the at least one breakpoint generating module to         be halted;     -   at least one halt controller coupled to one or more of the at         least one breakpoint generating module and being responsive to         said first breakpoint message, for allowing operation of said         one or more breakpoint generating modules to be halted; and     -   a core processor coupled to said at least one breakpoint         generating module and being responsive to a second breakpoint         message for allowing operation of said core processor to be         halted;     -   wherein the second breakpoint message corresponds to the first         breakpoint message; and     -   wherein the core processor generates a third breakpoint message         for allowing operation of the core processor and the at least         one breakpoint generating module to be halted.

Still further the invention provides a system for allowing a DMA (Direct Memory Access) controller to halt operation of at least one of a core processor and one or more breakpoint generating modules in a system providing mutual breakpoint capabilities, the system comprising:

-   -   at least one matching comparator responsive to at least one DMA         bus and corresponding to a matching condition, for indicating         when the matching condition is met; and     -   a DMA breakpoint generator coupled to the at least one matching         comparator and being responsive thereto for generating a DMA         breakpoint message capable of halting the operation of said core         processor when the matching condition is met.

The present invention further provides a system for allowing a timer to halt operation of at least one of a core processor and one or more breakpoint generating modules in a system providing mutual breakpoint capabilities, the system comprising:

-   -   a matching comparator responsive to a timer clock signal and         corresponding to a matching condition, for indicating when the         matching condition is met; and     -   a timer breakpoint generator coupled to the matching comparator         and being responsive thereto for generating a timer breakpoint         message capable of halting the operation of the at least one of         said core processor and one or more breakpoint generating         modules.

The present invention further provides a method for providing mutual breakpoint capabilities to at least one breakpoint generating module and a core processor in a computing device, the method comprising:

-   -   generating a first breakpoint message in one of the at least one         breakpoint generating module; and     -   conveying the first breakpoint message so as to allow halting         the operation of one or more of the at least one breakpoint         generating modules and the core processor.

Still further the invention provides a method for providing mutual breakpoint capabilities to at least one breakpoint generating module and a core processor in a computing device, the method comprising:

-   -   generating a third breakpoint message in one of the core         processor; and     -   conveying the third breakpoint message so as to allow halting         the operation of one or more of the at least one breakpoint         generating modules and the core processor.

In addition, the invention provides a method for halting operation of at least one breakpoint generating module and a core processor in a system providing mutual breakpoint capabilities in a computing device, the method comprising:

-   -   receiving a breakpoint message;     -   retrieving an indication stored in an enabler field of a halt         controlling register, the halt controlling register corresponds         to the breakpoint message;     -   if the indication indicated that operation of a module         respective of the enabler field is to be halted         -   generating a corresponding halt signal; and         -   conveying the corresponding halt signal so as to allow             halting the operation of the module.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to understand the invention and to see how it may be carried out in practice, a preferred embodiment will now be described, by way of non-limiting example only, with reference to the accompanying drawings, in which:

FIG. 1 is a block diagram illustrating a computer system implementing a direct memory access controller according to one embodiment of the invention;

FIG. 2 is a block diagram illustrating a system providing mutual breakpoint capabilities for halting the operation of a core processor and a DMA controller, according to one embodiment of the invention;

FIG. 3 is a block diagram illustrating a system providing mutual breakpoint capabilities for halting the operation of a core processor, a DMA controller and a timer, according to one embodiment of the invention;

FIG. 4 illustrates a circuit providing mutual breakpoint capabilities to the system of FIG. 3, according to one embodiment of the invention;

FIG. 5 is a block diagram illustrating an alternative system providing mutual breakpoint capabilities for halting the operation of a core processor, a DMA controller and a timer, according to one embodiment of the invention;

FIG. 6 illustrates a halt signal generator circuit that provides mutual breakpoint capabilities to the system of FIG. 5, according to one embodiment of the invention;

FIG. 7 is a flowchart illustrating a method for generating a first breakpoint message in a system providing mutual breakpoint capabilities, according to one embodiment of the invention;

FIG. 8 is a flowchart illustrating a method for generating a core breakpoint message in a system providing mutual breakpoint capabilities, according to one embodiment of the invention; and

FIG. 9 is a flowchart illustrating a method for halting operation of at least one breakpoint generating module and a core processor in a system providing mutual breakpoint capabilities, according to one embodiment of the invention.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

In the following description components that are common to more than one figure will be referenced by the same reference numerals.

FIG. 2 is a block diagram illustrating a system 201 providing mutual breakpoint capabilities for halting the operation of a core processor and a DMA controller, according to one embodiment of the invention. A core processor 102 is coupled to a breakpoint controller 202 that provides controller breakpoint messages 203 (constituting a “second breakpoint message”) thereto. One example for a controller breakpoint message can be a signal, such as a breakpoint signal known per se. The core processor 102 is responsive to the controller breakpoint message 203 for halting its operation. To this end, the core processor 102 can include an emulation module (not shown) as known to those versed in the art, which traps a controller breakpoint message 203 and changes the mode of operation of the core processor 102 to debug mode as known per se.

The breakpoint controller 202 responds to DMA breakpoint messages 204 received from a DMA controller 103 coupled thereto. When the breakpoint controller 202 receives a DMA breakpoint message 204, it generates a controller breakpoint message 203. It will be appreciated that the DMA breakpoint messages 204 can be, for example, a signal.

The DMA controller 103 provides DMA breakpoint messages 204 also to a clock controller 304. The clock controller 205 includes a clock generator 206 that provides clock ticks. The clock controller 205 provides clock signals corresponding to the clock ticks, to different entities in the system 201. Clock signals provided to the DMA controller 103 are referred to hereinafter as DMA clock signals 207. When the clock controller 304 receives a DMA breakpoint message 204, it prevents DMA clock signals 207 from reaching the DMA controller 103, thereby halting its operation. In other words, a person versed in the art can understand that by generating a DMA breakpoint message 204 the DMA controller 103 can halt the operation of the core processor and/or its own operation.

In addition, the clock controller 304 is coupled to the core processor 102. When the operation of the core processor is halted by a controller breakpoint message 203 it generates a core breakpoint message 208 (constituting a “third breakpoint message”) such as a breakpoint acknowledge known per se or any other signal that is then received by the clock controller 304. The clock controller 304 is responsive to the core breakpoint message 208 for preventing clock signals (including DMA clock signals 207) from reaching the DMA controller 103, in a mechanism described in detail below (see, for example FIG. 4) halting its operation thereby. That is, a person versed in the art will understand that by generating a core breakpoint message 208 the core processor 102 can halt the operation of the DMA controller 103. It should be appreciated that methods are known today by which the core processor 102 can halt its own operation. In addition, the core can halt its own operation in a way similar to this by which the DMA controller can halt the operation of the controller (e.g., via the clock controller 304) as will be explained with further details below.

It should also be noted that the core processor can halt the operation of the DMA controller 103 at any time, and not only as a consequence of entering a debug mode. Thus, breakpoint acknowledge is not the only type of core breakpoint message 208 allowed.

FIG. 2 illustrates a system allowing generation of mutual breakpoints for halting the operation of a core processor and a DMA controller. That is, the core processor can halt the operation of the DMA controller as well as its own operation while the DMA controller can halt the operation of the core processor as well as its own operation. The DMA controller constitutes a breakpoint generating module. However, sometimes there are other breakpoint generating modules being part of a mutual breakpoint generating system, such as a timer.

FIG. 3 is a block diagram illustrating such a system 301 providing mutual breakpoint capabilities for halting the operation of a core processor 102, a DMA controller 103 and a timer 302, according to one embodiment of the invention. The timer 302 generates a timer breakpoint message 303 when a measured time span expires. The breakpoint controller 202 is coupled to the timer 302 and is responsive to the timer breakpoint message 303 for generating a controller breakpoint message 203 that halts the operation of the core processor 102 as was previously explained with reference to FIG. 2.

It is noted that the DMA breakpoint message and/or the timer breakpoint message constitute a first breakpoint message. More generally, a breakpoint message generated by a breakpoint generating module is referred to as a first breakpoint message.

It should be noted that the timer breakpoint message 303 can be, for example, a signal. In addition, after realizing that other breakpoint messages (such as the controller breakpoint message 203, the DMA breakpoint message 204 or the core breakpoint message 208) can also be signals, it can be generally said that breakpoint messages can be realized, for example, in the form of signals known per se.

The timer 302 is coupled also to a clock controller 304 and is responsive to timer clock signals 305 that are generated thereby in addition to the DMA clock signals 207.

Upon receiving a timer breakpoint message 303, the clock controller 304 prevents clock signals (including DMA clock signals 207 and/or timer clock signals 305) from reaching the DMA controller 103, and/or the timer 302 in a mechanism described in detail below (see, for example FIG. 4), halting their operation thereby.

It is noted that in system 301 the DMA controller 103 can halt the operation of the core processor 102, the operation of the timer 302 (via the clock controller 304) and/or its own operation. Similarly, the core processor 102 can halt the operation of the DMA controller 103, the operation of the timer 302 and/or its own operation. Finally, the timer 302 can also halt the operation of the DMA controller 103, the operation of the core processor 102 as well as its own operation. That is, system 301 illustrates mutual breakpoint capabilities between the core processor 102, the DMA controller 103 and the timer 302.

Having demonstrated that mutual breakpoint capabilities can exist between different breakpoint generating modules (such as the DMA controller 103 and the timer 302) and a core processor 102 in a computing system (such as system 201 or 301), there will now be described with reference to FIG. 4 a circuit 401 providing mutual breakpoint capabilities to the system 301 of FIG. 3, according to one embodiment of the invention. It should be noted that the circuit 401 corresponds to the system 301 of FIG. 3. Yet, a person versed in the art will realize that the embodiment illustrated in FIG. 4 is non-limiting, and other circuits allowing mutual breakpoint capabilities, including other breakpoint generating modules, can also be employed, such as a circuit corresponding to system 201 (of FIG. 2).

It will be realized that the operation of a DMA controller (such as DMA controller 103) is allowed by receiving clock signals such as clock ticks or DMA clock signals 207 indicative thereof. In addition, it is known to those versed in the art that a DMA controller can access data (hereinafter “source data”) located at a certain source address, read the accessed data and write it (constituting “destination data”) to a destination address. This is illustrated as if the DMA controller 103 has four buses, namely “source address bus” 402, “destination address bus” 403, “source data bus” 404 and “destination data bus” 405. Generally the four buses are referred to as “DMA buses”.

In addition, the embodiment currently described illustrates generation of DMA breakpoint messages 204 corresponding to certain conditions occurring at the DMA controller 103 as will be described below. It should be noted that the embodiment is non-limiting and different conditions than those described below can also lead to the generation of a DMA breakpoint message 204.

According to the embodiment, conditions for generating a DMA breakpoint message include, for example, when the DMA controller detects a specific value (constituting “source value” or “source data”) in any source address; or when it detects a specific value (constituting “destination value” or “destination data”) in any destination address; or when it transfers any value from a specific source address, etc.

It will be appreciated that in order to detect when a condition occurs corresponding to which a DMA breakpoint message should be generated, the DMA controller 103 compares a certain value (hereinafter, “reference value”) with another value (constituting “temporal value”) that is currently accessed by the DMA controller for example via the four buses. In one of the examples above wherein the DMA is expected to generate a DMA breakpoint message when it accesses a specific source address, the temporal value is the source address currently accessed by the DMA, while the reference value is the specific source address. Sometimes more than one reference value exists. Reference values can be stored in registers generally referred to as “reference registers”.

In the embodiment illustrated in FIG. 4 there are four reference registers, namely a “source address reference register” 406, a “destination address reference register” 407, a “source data reference register” 408 and a “destination data reference register” 409. It should be realized that source address reference register 406 corresponds to source address bus 402, destination address reference register” 407 corresponds to destination address bus 403; source data reference register 408 corresponds to source data bus 404; and destination data reference register 409 corresponds to destination data bus 405. The correspondence between the reference registers and their respective buses is explained below with reference to matching comparators.

A “matching condition” is a logical term allowing comparison of the reference values stored in the reference registers with the respective temporal value indicated by the buses. It should be noted that a matching condition can use any logical operator applicable, such as equality (‘=’), greater than (‘>’), smaller than (‘<’), greater than or equal to (‘≦’) and others. The logical term can be hard-coded or programmable. Further below a convention is taken wherein a matching condition that is fulfilled is considered as evaluated as ‘true’ (for example, if A=5 and B=3 then the condition A>B evaluates as ‘true’), whereas a condition that is not fulfilled is considered as ‘false’ (in the previous example the condition B>A is evaluated as ‘false’). However, this is non-limiting and the opposite convention can be taken as well.

A “matching comparator”, associated with a matching condition, has at least one temporal value and at least one reference value accessible thereto. The embodiment of FIG. 4 illustrates four matching comparators, namely, a “source address matching comparator” 410, a “destination address matching comparator” 411, a “source data matching comparator” 412 and a “destination data matching comparator” 413. For the sake of simplicity, the correspondence of the matching comparators to the DMA buses and to the reference registers is illustrated in Table 1, wherein the matching comparator of each line corresponds to the DMA bus and the reference register of the same line.

TABLE 1 Matching comparator DMA bus Reference register source address matching source address source address reference comparator (410) bus (402) register (406) destination address destination destination address matching comparator address bus (403) reference register (407) (411) source data matching source data bus source data reference comparator (412) (404) register (408) destination data matching destination data destination data reference comparator (413) bus (405) register (409)

In other words, the matching condition associated with the source address matching comparator 410 compares the source address currently accessed by the DMA controller (i.e., the temporal value is represented by the value currently conveyed by the source address bus 402) with the address indicated by the corresponding source address reference register 406. Similarly, the matching condition associated with the destination address matching comparator 411 compares the temporal value represented by the destination address bus 403 (i.e., the destination address currently accessed by the DMA controller) with the address indicated by the corresponding destination address reference register 407 etc.

It should be noted that the described embodiment includes four DMA buses, four reference registers and four matching comparators. Yet, the number four is non-limiting and other embodiments can include a different number of buses, registers or comparators. In addition, the number of the buses is not necessarily similar to the number of matching comparators and a different number of reference registers can also be employed. For example, several different matching comparators can correspond to a single common DMA bus. Alternatively, a matching condition associated with a matching comparator can compare a value indicated by a single reference register (for example, ‘A’) to two different temporal values indicated by two different DMA buses (e.g., TemporalValueX and TemporalValueY) in a single logical expression (such as “TemporalValueX>A>TemporalValueY”).

According to one embodiment, the DMA controller 103 generates a DMA breakpoint message 204 whenever any one of the matching conditions evaluates as ‘true’. Alternatively, according to another embodiment of the invention, a reference register can include a breakpoint enabler field 414. The size of the breakpoint enabler field 414 can be any size. It is noted that the breakpoint enabler field 414 need not be included in the reference register but can be associated therewith by any method known in the art.

A breakpoint on/off switch, or shortly a “breakpoint switch”, is coupled to a matching comparator and to a corresponding breakpoint enabler field 414. A DMA breakpoint message is generated only when the respective breakpoint enabler field 414 indicates that the corresponding DMA breakpoint message generation is enabled (according to this embodiment, when the respective breakpoint enabler field 414 is set to 1) and the respective matching condition (the one associated with the matching comparator) evaluates to ‘true’. This is non-limiting of course, and any other convention is allowed as well, e.g., a DMA breakpoint message can be generated only when the respective breakpoint enabler field 414 is set to 0 and the respective matching condition (the one associated with the matching comparator) evaluates to ‘true’ etc.

In FIG. 4 there are four breakpoint switches illustrated (namely “source address breakpoint switch” 415, “destination address breakpoint switch” 416, “source data breakpoint switch” 417 and “destination data breakpoint switch” 418), each corresponding to a respective one of the matching comparators 410, 411, 412 and 413.

Alternatively (not illustrated in the figure), the matching comparator can be associated with the respective breakpoint enabler field 414, evaluating the matching condition only if the breakpoint enabler field 414 indicates that the corresponding DMA breakpoint message generation is enabled.

Thus, the breakpoint enabler field 414 allows controlling (that is, enabling and disabling) the operation of the corresponding matching comparator. More generally, an enabler field allows disabling or enabling the operation of a constituent of the system.

In the embodiments described so far a DMA breakpoint message is generated whenever any matching condition is evaluated as ‘true’ and its respective breakpoint enabler field 414 is set to 1. The comparators illustrated are associated with “simple” matching conditions, i.e., each condition corresponds to two parameters such as one DMA bus and one reference register. Yet, it can be appreciated that “composite” matching conditions are allowed, wherein one comparator is associated with more than two parameters. For example, two DMA buses and two reference registers. An example of a composite matching condition is “if a specific source address AND a specific destination address are accessed.” It will be appreciated that it is also possible to associate more than one enabler field with such a composite matching comparator. A DMA breakpoint message generated in accordance with a composite matching condition constitutes a composite DMA breakpoint message.

In a different embodiment the matching comparator can be associated with more than one DMA bus but with no reference register. Such a matching comparator can be associated with a matching condition such as “if source data ≠ destination data”, wherein a DMA breakpoint can be generated whenever the data changes between reading it from the source address and writing to the destination address.

In the embodiment of FIG. 4, the matching comparators are associated with simple matching conditions comparing one temporal value with one reference value. Yet, composite conditions for generating DMA breakpoint messages are allowed by providing a breakpoint selection register 419, encoding the combination of matching conditions that should evaluate as ‘true’ in order to generate a DMA breakpoint message 204. For example, if the breakpoint selection register 419 is considered as a bit field, then every bit therein corresponds with a matching condition (i.e., with a matching comparator associated therewith). A bit set to 1 in the breakpoint selection register 419 indicates that the corresponding matching condition should evaluate to ‘true’ in order to generate a DMA breakpoint message. As was mentioned before, here also the opposite policy is allowed.

The breakpoint selection register 419 and the breakpoint switches (415, 416, 417 and 418) are coupled to a selection comparator 420. In an embodiment where there are no breakpoint switches, the selection comparator 420 is coupled directly with the matching comparators.

The selection comparator 420 generates (or allows the DMA controller 103 to generate) a DMA breakpoint message 204 only when all those breakpoint switches whose corresponding bits in the breakpoint selection register 419 are set to 1 are evaluated as ‘true’ and enabled.

It is appreciated that the size of the breakpoint selection register 419 can be any number of bits applicable to the case. However, according to the current example the breakpoint selection field size is four bits, corresponding to the number of matching comparators. Yet, this embodiment is non-limited and it should be appreciated that any other correspondence is also applicable. For example, there may be an embodiment where two bits are used to indicate whether a certain matching condition should be evaluated as ‘true’.

In the following Table 2 are listed possible values indicated by the breakpoint selection register 419 and the corresponding matching conditions that should evaluate to ‘true’ in order for the selection comparator 420 to generate a DMA breakpoint message.

TABLE 2 Breakpoint selection Matching conditions register source data matching comparator 0001 destination data matching comparator 0010 source address matching comparator 0100 destination address matching comparator 1000 source data AND destination data matching comparators 0011 source data AND source address matching comparators 0101 source data AND destination address matching 1001 comparators destination data AND source address matching 0110 comparators destination data AND destination address matching 1010 comparators source address AND destination address matching 1100 comparators source data AND destination data AND source address 0111 matching comparators source data AND destination data AND destination 1011 address matching comparators source data AND source address AND destination 1101 address matching comparators destination data AND source address AND destination 1110 address matching comparators Source data AND destination data AND source address 1111 AND destination address matching comparators

In the example of Table 2 a combination of one or more matching conditions were illustrated wherein AND conditions were used. It should be noted that in a different embodiment, OR conditions can be used as well, such as “destination address OR source address” etc. This is non-limiting and any condition that applies can be sued instead.

Thus, the selection comparator 420 evaluates the matching conditions in accordance with the breakpoint selection register 419. In the embodiment described above a DMA breakpoint message is generated whenever all the matching conditions corresponding to one-bits (i.e., bits whose value is ‘one’) in the breakpoint selection register 419 are evaluated as ‘true’. Other matching conditions can evaluate as ‘true’ or as ‘false’, not affecting the generation of the DMA breakpoint message. Yet a different embodiment allows determining if a matching condition corresponding to a zero bit in the breakpoint selection register 419 must be ‘false’ or can be evaluated to any value whatsoever. According to this embodiment, there is an exclusiveness field 421 coupled to the selection comparator 420. The exclusiveness field 421 includes, for example, bits, wherein each bit corresponds to one bit in the breakpoint selection register 419, i.e, the exclusiveness field 421 contains an equal number of bits as the breakpoint selection register 419.

The bits in the exclusiveness field 421 indicate whether zero-bits (i.e., bits whose value is ‘zero’) in the breakpoint selection register 419 are to be considered exclusively. That is, if a bit in the breakpoint selection register 419 is zero while the corresponding matching condition is ‘true’, whether or not the selection matching comparator 415 should generate a DMA breakpoint message 204.

In other embodiments, such as the embodiment of FIG. 4, the DMA breakpoint messages 204 are generated by a DMA breakpoint generator 436 and not by the selection matching comparator 415. The DMA breakpoint generator 436 is responsively coupled to the selection comparator 420. When the selection comparator indicates that the DMA should generate a DMA breakpoint, the DMA breakpoint generator 436 generates it. However, this is non-limiting and it will be appreciated that when a DMA breakpoint generator 436 does not exist, the module where the DMA breakpoint is generated (such as the selection comparator 420 mentioned in the example above) is considered as a DMA breakpoint generator.

Turning now to the timer 302 (see FIG. 3), it is considered that the timer actually allots time, or more specifically, generates a timer breakpoint message 303 when a measured time span expires. In order to allot time, the timer includes a timer counter 422 and a timer condition 423. As will be appreciated by a person versed in the art, the timer counter can store a value used for counting.

Referring again to FIG. 3, it was described before that the timer is responsive to the timer clock signal 305 generated by the clock controller 304. When initializing the timer 302 the timer counter 422 is set to indicate the number of clock signals expected before the time span expires.

When the timer receives a timer clock signal 305 the value stored in the timer counter 422 is decreased by one. In addition, the timer comparator 423 compares the current value stored in the timer counter 422 with zero. When the timer comparator 423 finds that the value stored in the timer counter 422 is zero, a timer breakpoint message 303 is generated. The timer breakpoint is generated by a timer breakpoint generator 437 responsive to the timer comparator 423.

It will be appreciated that in an alternative embodiment a different allotting policy can be used. For example, when the timer 302 is initialized, the value store in the timer counter 422 is set to zero while the timer comparator 423 is programmed to indicate the number of clock signals expected before the time span expires (an “allotted value”). In every clock signal the value stored in the timer counter 422 is increased. When the timer comparator 423 detects that the value stored in the timer counter 422 is equal to the allotted value, a timer breakpoint message is generated.

It will be appreciated that in an alternative embodiment a different allotting policy can be used. For example, when the timer 302 is initialized, the value stored in the timer counter 422 is set to zero while the timer comparator 423 is programmed to indicated the number of clock signals expected before the time span expires (an “allotted value”). In every clock signal the value stored in the timer counter 422 is increased. When the timer comparator 423 detects that the value stored in the timer counter 422 is equal to the allotted value, a timer breakpoint message is generated.

Referring back to the description of the DMA controller 103 and to the description of the reference registers (such as 406-408), an analogy can be made. That is, the timer counter 103 can be considered as a reference register, while the timer comparator 423 can be considered as a match comparator.

It should be further appreciated that the timer can also include a timer breakpoint enabler field 424, having a functionality that resembles that of the breakpoint enabler field 414, that is, to toggle an on/off switch 425, allowing or preventing the generation of timer breakpoint messages 303 thereby.

It was already explained, with reference to FIGS. 2 and 3, that the DMA controller 103 and the timer 302 are responsively coupled to the clock controller 304 for receiving respectively DMA clock signals 207 and timer clock signals 305 therefrom. It was also explained that by halting the respective clock signals the clock controller 304 half the operation of the DMA controller and the timer 302. In addition, it was mentioned that the clock controller 304 is responsively coupled to the DMA controller 103, timer 302 and core processor 102 for receiving DMA breakpoint messages 204, timer breakpoint messages 303 and core breakpoint messages 208, respectively.

FIG. 4 illustrates that the clock controller 304 includes three halt controlling registers (hereinafter referred to also as “clock control registers”), namely “timer controlled halt register” 426, “DMA controlled halt register” 427 and “core controlled halt register” 428. Each of the clock control registers includes or is associated with a DMA halt enabler field 429 and a timer halt enabler field 430. Both the DMA halt enabler field 429 and the timer halt enabler field 430 can be one bit or larger in size.

The clock controller 304 also includes a DMA clock signal generator 431 and a timer clock signal generator 432. The DMA clock signal generator 431 and the timer clock signal generator 432 are coupled to the clock generator 206, for generating clock signals such as DMA clock signals 207 and timer clock signals 305 in response to receiving clock ticks therefrom.

When the clock controller 304 receives a DMA breakpoint message 204, the DMA controlled halt register 427 and its associated enabler fields 429 and 430 are checked. If the DMA halt enabler field 429 indicates that halting the DMA is enabled, the operation of the DMA clock signal generator 431 is halted, thereby halting the generation of DMA clock signals 207. The DMA controller 103 receives no clock signals, and its operation is halted. Operation can be resumed, for example, by re-setting the DMA halt enabler field 429 to indicate that halting the DMA is disabled. This can be done, for example, by the core processor (or by a programmer operating the core processor), as known to those versed in the art. Similarly, if the timer halt enabler field 430 indicates that halting the timer is enabled, the operation of the timer clock signal generator 432 is halted, thereby halting the generation of timer clock signals 305. The timer 302 receives no clock signals, and its operation is halted. Operation can be resumed, for example, by re-setting the timer halt enabler field 430 to indicate that halting the timer is disabled.

Similar mechanisms allow the clock controller 304 to respond to timer breakpoint messages 303 and core breakpoint messages 208. When the clock controller 304 receives a timer breakpoint message 303, the timer controlled halt register 426 and its associated enabler fields 429 and 430 are checked. If the DMA halt enabler field 429 indicates that halting the DMA is enabled, the operation of the DMA clock signal generator 431 is halted, thereby halting the generation of DMA clock signals 207. The DMA controller 103 receives no clock signals, and its operation is halted. Operation can be resumed, for example, by re-setting the DMA halt enabler field 429 to indicate that halting the DMA is disabled. Similarly, if the timer halt enabler field 430 indicates that halting the timer is enabled, the operation of the timer clock signal generator 432 is halted, thereby halting the generation of timer clock signals 305. The timer 302 receives no clock signals, and its operation is halted. Operation can be resumed, for example, by re-setting the timer halt enabler field 430 to indicate that halting the timer is disabled.

When the clock controller 304 receives a core breakpoint message 208, the core controlled halt register 428 and its associated enabler fields 429 and 430 are checked. If the DMA halt enabler field 429 indicates that halting the DMA is enabled, the operation of the DMA clock signal generator 431 is halted, thereby halting the generation of DMA clock signals 207. The DMA controller 103 receives no clock signals, and its operation is halted. Operation can be resumed, for example, by re-setting the DMA halt enabler field 429 to indicate that halting the DMA is disabled. Similarly, if the timer halt enabler field 430 indicates that halting the timer is enabled, the operation of the timer clock signal generator 432 is halted, thereby halting the generation of timer clock signals 305. The timer 302 receives no clock signals, and its operation is halted. Operation can be resumed, for example, by re-setting the timer halt enabler field 430 to indicate that halting the timer is disabled.

It should be appreciated that in other embodiments, where other breakpoint generating modules are coupled to the mutual breakpoint generating system, the clock controller 304 includes a corresponding clock control register and a corresponding clock signal generator for each breakpoint generating module. In addition, an enabler field controlled by each breakpoint generating module is associated with each clock control register. The circuit and mechanism described above with reference to the clock control 304 can apply then to any number of breakpoint generating modules.

Turning now to the breakpoint controller 202, it was previously mentioned with reference to FIGS. 2 and 3 that the breakpoint controller 202 is responsively coupled to the DMA controller 103 and to the timer 302, for receiving respective breakpoint messages (i.e., DMA breakpoint messages 204 and timer breakpoint messages 303) therefrom. Generally, the breakpoint controller is responsive to respective breakpoint messages received from breakpoint generating modules coupled thereto.

The breakpoint controller 202 also includes, or is associated with, a core halt enabler field 433. When the breakpoint controller 202 detects on 434 that at least one breakpoint message is received, and on 435 that the core enabler field 433 indicates that halting core operation is enabled, a controller breakpoint message 203, such as a breakpoint signal known per se is generated and fed to the core processor 102. When the core receives a controller breakpoint message 203 it enters a debug mode as known to those versed in the art.

The clock controller 304 described so far is one non-limiting example for providing a way to halt the operation of breakpoint generating modules. Other embodiments are possible as will now be described with reference to FIGS. 5 and 6. Therefore the general term “halt controller” is used hereinafter. That is, the clock controller 304 is one embodiment of a halt controller.

FIG. 5 shows such an alternative system 501 that provides mutual breakpoint capabilities and includes a halt signal generator that serves as a halt controller. A DMA controller 103, conveying DMA breakpoint messages 204 (a DMA breakpoint message can constitute a “first breakpoint message”, as was previously noted) is coupled to a breakpoint controller 202. The breakpoint controller 202, is coupled to a core processor 102, conveying controller breakpoint messages 203 thereto. A controller breakpoint message 203 constitutes a “second breakpoint message”.

A timer 302, conveying timer breakpoint messages 303, is also coupled to the breakpoint controller 202. A timer breakpoint message 303, can also constitute a “first breakpoint message” as was previously explained.

A halt signal generator 502 is coupled to the DMA controller 103, to the timer 302 and to the core processor 102, receiving their respectively conveyed DMA breakpoint messages 204, timer breakpoint messages 303 and core breakpoint messages 208. The halt signal generator 502 conveys halt signals to (such as a DMA halt signal 503 and/or a timer halt signals 504) to the DMA controller 103 and to the timer 302.

FIG. 6 illustrates a halt signal generator circuit providing mutual breakpoint capabilities to the system of FIG. 5, according to one embodiment of the invention. Like the clock controller 304, the halt signal generator 502 includes three halt controlling registers, namely, a timer controlled halt register 426, a DMA controlled halt register 427 and a core controlled halt register 428. Each of the halt controlling registers includes or has associated therewith a DMA halt enabler field 429 and a timer halt enabler field 430. Both the DMA halt enabler field 429 and the timer halt enabler field 430 can be one bit or larger in size.

According to the embodiment the halt signal generator 502 includes also a DMA halt signal generator 601 and a timer halt signal generator 602 for generating DMA halt signals 503 and timer halt signals 504 respectively. When the halt signal generator 502 receives a timer breakpoint message 303, the timer controlled halt register 426 and its associated enabler fields 429 and 430 are checked. If the DMA halt enabler field 429 indicates that halting the DMA is enabled, the DMA halt signal generator 601 generates a DMA halt signal 503 that is conveyed to the DMA controller 103. Similarly, if the timer halt enabler field 430 indicates that halting the timer is enabled, the timer halt signal generator 602 generates a timer halt signal 504 that is conveyed to the timer 302.

Likewise, the DMA controlled halt register 427 together with a DMA breakpoint message 204 received at the halt signal generator 502 are used to determine if a halt signal should be generated by the DMA halt signal generator 601 or by the timer halt signal generator 602, while the core halt register 428 is used for the same in combination with a core breakpoint message 208 received at the halt signal generator 502.

Halting modules such as the breakpoint generating modules (DMA controller and timer in this example), i.e., disabling their operation, is known in the art, as illustrated, e.g., by above-mentioned U.S. Pat. No. 5,978,860. In addition it should be appreciated that operation can be resumed (i.e., enabled), for example, by re-setting the DMA halt enabler field 429 to indicate that halting the DMA is disabled.

Following the description above it will be appreciated that in the described embodiment one halt controlling register (such as the DMA controlled halt register 427) is used for controlling the operation of more than one breakpoint generating module. In this example, the DMA controlled halt register 427 controls the operation of both the DMA controller 103 and the timer 302, wherein the number of enabler fields corresponds to the number of controlled breakpoint generating modules. It should be realized therefore that in a different embodiment the number of breakpoint generating modules controlled by a halt controlling register can vary. For example, in a different embodiment of the invention, one halt controlling register can be used for controlling the operation of only one breakpoint generating module. In this case it is possible to have more than one halt controlling register that respond to a single breakpoint message. Further more, in yet a different embodiment there can be more than one halt controlling register, wherein each halt controlling register controls a different number of breakpoint generating modules.

In addition, in the embodiment of FIG. 6, the halt controlling registers are in direct association or included in the halt signal generator 502 that is the single halt signal generator in the system. However, it should be realized that in yet a different embodiment, a halt signal generator 502 can be directly associated with or included in a breakpoint generating module. That is, a breakpoint generating module can include or be in direct association with one ore more halt controlling registers, wherein the breakpoint messages are conveyed directly to the breakpoint generating modules (i.e., directly to the halt signal generator 502 in association therewith). It is noted that a combination is also allowed, i.e., some breakpoint generating modules can be in direct association with their respective halt signal generator, while the operation of other breakpoint generating modules can be controlled by a common halt signal generator, as illustrated in FIGS. 5 and 6. Further more, it should be realized that one or more signal generators can be combined with one or more clock controllers to halt the operation (i.e., disable) of breakpoint generating modules in the system. Thus, realizing that a clock controller and a halt signal generator are two non-limiting examples of a halt controller, it should be appreciated that in a system providing mutual breakpoint capabilities there should be at least one halt controller.

Further more, a person versed in the art can appreciate that the breakpoint controller 202 too can be considered as a halt controller. The a core halt enabler field 433 can be considered as a halt controlling register or it can be associated with a halt controlling register while the controller breakpoint message 203 is the halt signal in this case. The breakpoint controller 202 can include a core signal generator that generates controller breakpoint messages. It should be realized that in alternative embodiments the breakpoint controller's circuit can be combined together with the halt controller's circuit as illustrated in FIGS. 4 and 6, for example.

Turning now to FIG. 7, the figure provides a flow chart illustrating a method for generating a first breakpoint message in a system providing mutual breakpoint capabilities, according to one embodiment of the invention. After generating (701) a first breakpoint message in a breakpoint generating module, the breakpoint message is conveyed (702) to other modules in the system, such as the core processor 102, the halt controller (such as the halt signal generator 502, the clock controller 304 the breakpoint controller 202) or even to breakpoint generating modules (possibly including the one where the first breakpoint message was generated). As was previously described with reference to FIGS. 2-6, examples to breakpoint generating modules are the DMA controller 103 and the timer 302, while examples to their respectively generated first breakpoint message are a DMA breakpoint messages 204 and a timer breakpoint message 303. Yet these examples are non-limiting and other types of a first breakpoint message as well as other breakpoint generating modules are also possible. The first breakpoint message is conveyed so as to allow halting the operation of one or more of the at least one breakpoint generating modules and the core processor.

It was previously explained that the core processor 102 can generate a core breakpoint message, referenced also as a “third breakpoint message”, for allowing the operation of the at least one breakpoint generating modules and core processor to be halted. This is illustrated in FIG. 8 that is a flowchart illustrating a method for generating a core breakpoint message in a system providing mutual breakpoint capabilities, according to one embodiment of the invention.

After generating (801) a third breakpoint message in a breakpoint generating module, the breakpoint message is conveyed (802) to other modules in the system, such as the halt controller (such as the halt signal generator 502, the clock controller 304 the breakpoint controller 202), directly to the breakpoint generating modules, or even the core processor 102 itself. As was previously described with reference to FIGS. 2-6, examples to breakpoint generating modules are the DMA controller 103 and the timer 302. Yet these examples are non limiting and other breakpoint generating modules are also possible. The third breakpoint message is conveyed so as to allow halting the operation of one or more of the at least one breakpoint generating modules and/or the core processor.

FIG. 9 is a flowchart illustrating a method for halting operation of at least one breakpoint generating module and a core processor in a system providing mutual breakpoint capabilities, according to one embodiment of the invention. After receiving a breakpoint message (901), or more specifically, after receiving a first or a third breakpoint message, if (902) an indication stored in any of the enabler fields (for example, 429, 430 or 433) of the breakpoint message's corresponding halt controlling register indicates that the operation of its respective module should be halted, a halt signal is generated (903) and is conveyed (904) in order to halt the operation of the breakpoint generating module or the operation of its respective core processor.

It should be noted that the received breakpoint message can be either a first or a third breakpoint message or a third or a third breakpoint message. In addition, it should be noted that in the exemplary embodiments provided above, the DMA halt enabler field 429, the timer halt enabler field 430 and the core enabler field 433 are examples of enabler fields. Further more, the modules are the DMA controller, the timer and the core processor respectively. Yet, this embodiment is non limiting and other breakpoint messages, other enabler fields and other modules are allowed as well.

It should be further noted that if the halt controller is a clock controller, the halt signal generated in 903 is conveyed (in 904) to the corresponding clock signal generator (e.g., the DMA clock signal generator 431 and a timer clock signal generator 432) that halt the operation of the breakpoint generating module or the core processor. 

1. A system for allowing a DMA controller to halt operation of a core processor and one or more breakpoint generating modules other than said core processor in a system providing mutual breakpoint capabilities, the system comprising: at least one matching comparator responsive to at least one DMA bus and corresponding to a matching condition relating to reference values stored in reference registers of said DMA controller, for indicating when the matching condition is met; and a DMA breakpoint generator coupled to the at least one matching comparator and being responsive thereto for generating a DMA breakpoint message capable of halting the operation of said core processor and one or more breakpoint generating modules when the matching condition is met.
 2. The system of claim 1, wherein one or more of the at least one matching comparator is coupled with an enabler field.
 3. The system of claim 1, wherein the at least one matching comparators are coupled with a breakpoint selection register for allowing composite matching conditions.
 4. The system of claim 1, wherein one of the one or more breakpoint generating modules is said DMA controller.
 5. The system of claim 1, wherein one of the one or more breakpoint generating modules is a timer.
 6. A method for halting operation of at least one breakpoint generating module being other than a core processor in a system providing mutual breakpoint capabilities in a computing device, the method comprising: receiving a breakpoint message generated by one of (i) a DMA breakpoint generator (ii) a timer breakpoint generator and (iii) a core processor; retrieving an indication stored in an enabler field of a halt controlling register, the halt controlling register corresponds to the breakpoint message; if the indication indicates that operation of a breakpoint generating module respective of the enabler field is to be halted, halting operation of the breakpoint generating module by halting operation of a clock signal generator respective of the breakpoint generating module, thereby halting generation of clock signals conveyable to the breakpoint generating module.
 7. The method of claim 6, wherein the breakpoint message is a first breakpoint message.
 8. The method of claim 7, wherein the enabler field is a DMA halt enabler field.
 9. The method of claim 7, wherein the enabler field is a timer halt enabler field.
 10. The method of claim 7, wherein the module is a DMA controller.
 11. The method of claim 7, wherein the module is a timer.
 12. The method of claim 6, wherein the breakpoint message is a third breakpoint message.
 13. A method for allowing a DMA (Direct Memory Access) controller to halt operation of a core processor and one or more breakpoint generating modules other than said core processor thus providing mutual breakpoint capabilities, the method comprising: comparing reference values stored in reference registers of said DMA controller and indicating when a matching condition is met; and generating a DMA breakpoint message responsive to said matching condition, said DMA breakpoint message is capable of halting the operation of said core processor and one or more breakpoint generating modules.
 14. A system for allowing one of (i) a DMA breakpoint generator (ii) a timer breakpoint generator and (iii) a core processor to halt operation of at least one or more breakpoint generating modules in a system providing mutual breakpoint capabilities in a computing device, the system comprising: a clock controller (304) receiving a breakpoint message generated by one of (i) a DMA breakpoint generator(ii) a timer breakpoint generator and (iii) a core processor (102) said clock controller (304) operative to retrieve an indication stored in an enabler field of a halt controlling register, the halt controlling register corresponds to the breakpoint message; said clock controller further operative to halt operation of the breakpoint generating module by halting operation of a clock signal generator respective of the module, thereby halting generation of clock signals conveyable to the module. 